The world of Avatar: The Last Airbender is a fantasy planet where civilization is divided into four great nations, each associated with an element: water, earth, fire, and air. Some people possess the ability to control (or "bend") one of these elements through martial arts and a deep spiritual connection.
It is a world where nature and spirits play a fundamental role. There are forests, deserts, mountains, volcanoes, oceans, and immense ancient temples, as well as the Spirit World, a parallel dimension inhabited by supernatural beings. Although there are technological advances like airships, submarines, trains, and steam-powered machinery, most of the world retains a traditional lifestyle inspired by various Asian and Indigenous cultures.
During this period, the world is immersed in a war that began one hundred years ago, when Fire Lord Sozin started a campaign of conquest to expand the power of the Fire Nation. Since then, the balance between the nations has been severely disrupted, making the restoration of peace and harmony a necessity for the entire world.